Method and system for controlling the temperature of an indoor space

ABSTRACT

A method for automatically operating a heating system includes operating a thermostat at a set point having a default set point value, automatically receiving an indoor temperature signal from an indoor temperature sensor, automatically receiving an outdoor weather indicator signal representing a measured or predicted outdoor weather condition, based on the outdoor weather indicator signal, determining a factor affecting heat flow out of water pipes adjacent to an indoor space, comparing the factor affecting heat flow to a pre-determined freeze protection point, based on the comparison, determining whether to maintain the set point at the default set point or to raise the set point to a computed set point higher than the default set point, and using the thermostat to automatically control the heating system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser.No. 62/141,347, filed Apr. 1, 2015, entitled “SYSTEM AND METHOD FORCONTROLLING THE TEMPERATURE INSIDE A BUILDING BASED ON THE TEMPERATUREOUTSIDE THE BUILDING,” and U.S. Provisional Application Ser. No.62/146,288 filed Apr. 11, 2015, entitled “SYSTEM AND METHOD FORCONTROLLING THE TEMPERATURE INSIDE A BUILDING BASED ON THE TEMPERATUREOUTSIDE THE BUILDING” each of which is incorporated herein by referencein its entirety.

BACKGROUND

Field

This disclosure relates to heating control systems, and methods forcontrolling heating systems. More particularly, the disclosure describesheating control systems, and methods of controlling heating systems,which use weather information to achieve energy savings.

Description of Related Art

Thermostats and Heating Control Systems

Conventional temperature control systems often use thermostats to allowthe user to create predetermined set points for indoor temperatures. Athermostat samples the temperature within a structure, and calls forheat or cooling from a heating, cooling, or HVAC system. Thermostats areused with all manner of heating, cooling and HVAC systems; and thesettings on the thermostat are usually driven by considerations for thecomfort or safety of the occupants of the structure. The temperature ina structure can be managed by one or more temperature control system,and by one or more heating, cooling or HVAC system. Either or both ofthe temperature control system or heating control system can bestand-alone, or can be a part of a building management system.

Current thermostats can be programmable to allow set points to beprogrammed for specific times of day, and for days of week. These timesand set points can correspond to when the user expects the building tobe occupied, when the occupants are expected to be away such as duringthe workday, or when they are typically asleep.

More recently-developed thermostats can regulate energy usage inresponse to peak demands on the power grid. Such thermostats call for,for example, less cooling in a structure when the power grid is at peakusage, and some thermostats of this type are also able to sense whethera structure is occupied, and even further reduce power consumptionduring times of peak demand if the structure is unoccupied.

Other recently-developed thermostats use the future occupancy status ofthe structure to determine set points for the temperature of the space.For example, a thermostat can receive a signal via the internetindicating that an occupant will soon arrive at the structure, andadjust its temperature set point accordingly. In other cases, based onhistorical data regarding occupants' movement in the structure, athermostat will predict when the structure will be occupied, and adjustits temperature set point accordingly. For structures which areregularly occupied, these technologies, alone or in combination, areboth energy efficient and ensure optimal comfort of the occupant of thestructure.

Outdoor temperature, or forecasts thereof, are currently used bynumerous heating control systems in a variety of ways, for example: tomerely display the temperature to users, to calculate mechanical heatlag (MHL) to determine when a system needs to be activated to achieve atarget temperature by a predetermined time, to determine thethermodynamic properties of a building, to evaluate the efficiency of aheating system over time, as a variable in a demand response systemwhich primarily shifts start and stop times, as a variable considered ina fresh air ventilation (FAV) controller, or as an indicator of howenergized a boiler system needs to be to have the thermal capacity toheat a space.

Unoccupied Structures

None of the above-described thermostat functionalities, however,addresses the need for energy-efficient heating of unoccupiedstructures. According to the U.S. Census Bureau estimates, there wereapproximately 17.3 million vacant housing units in the United States asof the first quarter of 2015.

In colder climates throughout the world, such unoccupied structures areunnecessarily heated in order to prevent damage to the structure fromcold, in particular from freezing pipes. Second homes, vacation homes,offices, any structures left unoccupied for extended periods, and evenparticular zones within a structure that are expected to have longerperiods of time where they are unoccupied, can benefit from a systemwhich will heat the space within the structure enough to prevent damagefrom cold, without unnecessarily heating the space. In these situations,the comfort of an occupant is not the objective; rather, a combinationof energy savings and prevention of damage to the structure caused bythe temperature is. Currently, the temperature in such unoccupiedstructures is usually set to a single pre-selected set point, and thespace within the structure is kept consistently at that temperature. Incolder climates, this pre-selected set point is selected because it willkeep the space within the structure warm enough to prevent damage to thestructure from cold, for example from freezing pipes. A typical fixedsetting of 50-65 degrees Fahrenheit is often selected for suchsituations. (The lowest recommended setting, per the American Red Cross,as well as major insurance companies and others, is to 55 degreesFahrenheit while buildings are vacant.) Such a setting is high enough tokeep the unoccupied structure safe during periods of extremely lowtemperatures, when there is a risk of damage to the structure, forexample from freezing pipes. Decreasing the indoor temperature from 68degrees Fahrenheit to 55 degrees Fahrenheit (a difference of 13 degreesFahrenheit) produces estimated savings of 39% in these unoccupiedstructures. (The U.S. Department of Energy estimates up to 1% savings onheating for each 1 degree Fahrenheit of setback for an eight hourperiod. Estimating savings for unoccupied spaces over a whole day wouldtherefore mean 24 hours per day savings or 3% savings per 1 degreesetback.)

In times of only moderately low temperatures, however, for example, whenoutdoor temperatures are 35-50 degrees Fahrenheit, a thermostat settingof 55 degrees Fahrenheit causes heating of the unoccupied structurewhich is not necessary to prevent damage. A further 15-20 degreereduction in indoor temperature set point (from 55 to 40 or 35 degreesFahrenheit) could yield significant savings: approximately 45-60% of theestimated energy currently being expended to heat unoccupied homes.Therefore, a vast amount of energy is wasted worldwide. On most days,structures that are expected to be unoccupied for longer periods arekept much warmer than would be necessary to prevent plumbing andproperty damage.

In many unoccupied structures, the default temperature setting, andtherefore the amount of energy used to heat the space, could bedramatically lowered if the thermostat in the structure could reliablyand automatically adjust the thermostat set point upward when outdoortemperatures decline and the chance of damage from cold increases.Currently, heating control systems are not available with thisfunctionality. There therefore remains a significant need for a methodof controlling the heating of a structure which considers outdoortemperature and provides enough heating to prevent damage to thestructure from cold, but without expending unnecessary energy.

SUMMARY

The present disclosure provides a method for controlling a heatingsystem. The method can include obtaining an outdoor temperatureindicator signal in proximity to the heating system and an indoor space.When the outdoor temperature indicator is at or above a freezeprotection point; a chosen set point is selected by selecting a defaultset point. When the outdoor temperature indicator is below a freezeprotection point, the method can include determining a computed setpoint based on the outdoor temperature indicator, comparing the computedset point to the default set point and a maximum set point and selectinga chosen set point by selecting (1) the default set point if thecomputed set point is below the default set point, (2) the computed setpoint, if the computed set point is between the default set point andthe maximum set point, or (3) the maximum set point, if the computed setpoint is above the maximum set point. The method can further includecontrolling the heating system to regulate the temperature of the indoorspace according to the chosen set point.

In controlling a heating system, the computed set point can increasemonotonically as the outdoor temperature decreases. The computed setpoint can be further based on one or more scaling factors. Such ascaling factor can be selected from the group consisting of a firstorder factor and a higher order factor.

In controlling a heating system, the outdoor temperature indicator canbe selected from a measured outdoor temperature, a forecasted outdoortemperature, a calculated outdoor wind chill, and a forecasted outdoorwind chill. If the outdoor temperature indicator is not available, theheating system can select a fail-safe set point. The outdoor temperatureindicator signal can be obtained via a network, such as the Internet;and can be a temperature obtained from a weather data provider or anoutdoor temperature sensor co-located at the site of the indoor space.

The present disclosure further provides a heating control system. Theheating control system can include at least one user interface. Theheating control system can include at least one computer. The computercan be programmed to obtain an outdoor temperature indicator signal inproximity to the heating system and an indoor space. When the outdoortemperature indicator is at or above a freeze protection point, theheating control system can select a chosen set point by selecting adefault set point. When the outdoor temperature indicator is below thefreeze protection point, the heating control system can determine acomputed set point based on the outdoor temperature indicator, comparethe computed set point to the default set point and a maximum set point,and select the chosen set point by selecting (1) the default set pointif the computed set point is below the default set point, (2) thecomputed set point, if the computed set point is between the default setpoint and the maximum set point, (3) the maximum set point, if thecomputed set point is above the maximum set point. The heating controlsystem can then control the heating system to regulate the temperatureof the indoor space according to the chosen set point.

In the heating control system, the computed set point can increasemonotonically as the outdoor temperature decreases. The computed setpoint can be further based on one or more scaling factors. Such ascaling factor can be selected from the group consisting of a firstorder factor and a higher order factor.

In the heating control system, the outdoor temperature indicator can beselected from a measured outdoor temperature, a forecasted outdoortemperature, a calculated outdoor wind chill, and a forecasted outdoorwind chill. If the outdoor temperature is not available, the heatingsystem can select a fail-safe set point. The outdoor temperatureindicator can be obtained via a network, such as the Internet, and canbe a temperature obtained from a weather data provider or an outdoortemperature sensor co-located at the site of the indoor space.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive body of work will be readily understood by referring tothe following detailed description in conjunction with the accompanyingdrawings, and as set out in the appended claims.

FIG. 1 is a diagram showing the data flow for on-site temperature,heating control system signaling, user interfaces, and Internet weatherinformation.

FIG. 2 is a diagram showing a possible configuration for a userinterface screen for the method.

FIG. 3 is a flow diagram showing an exemplary functional logic which theheating control system can employ.

FIG. 4 is a graph illustrating the inverse relationship between heatingsystem set points and various outdoor temperature readings that canresult from activating the heating control system during periods ofcolder outdoor temperatures. It shows in detail two exemplarymathematical functions that can result from using the described method.

FIG. 5 is a graph illustrating the inverse relationship between heatingsystem set points and various outdoor temperature readings that canresult from activating the heating control system during periods ofcolder outdoor temperatures. It shows in detail an exemplarymathematical function that can result from utilizing this logic.

FIG. 6 shows a conventional fixed setback using a set point of 55° F. Incontrast, an example of the set points resulting from utilizing oneembodiment is shown.

FIG. 7 shows a comparison of estimated relative costs for threedifferent fixed thermostat settings. Costs are based on the USDepartment of Energy's approximation for savings achieved by turningdown a thermostat during the heating season.

FIG. 8 shows three possible functions that describe a computed setpoint: one straight linear function, one curvilinear function, and one astepped function.

DETAILED DESCRIPTION

In colder climates, the freezing and subsequent bursting of pipes can bea significant problem. In an occupied structure, such as a home oroffice, the space within the structure is usually heated sufficiently tokeep the occupants of the structure comfortable. Temperatures that arehigh enough to keep the occupants of a structure comfortable, forexample, a temperature at or above 65 degrees Fahrenheit, are usuallysufficient to prevent damage to the structure due to cold, for example,to prevent the pipes within the structure from freezing.

In unoccupied structures, however, for example in homes in which no oneis resident, or unoccupied commercial or storage structures, thetemperature is usually kept at a fixed point, and left for the durationof the time that the structure remains unoccupied. The reason for thisaction is to prevent damage from extremely low temperatures inside thestructure; specifically, to prevent the freezing of water in, andsubsequent bursting of, pipes. A reasonable set point for an unoccupiedstructure using a standard thermostat is often between about 50-65degrees Fahrenheit. Such a set point means that when outdoortemperatures are at or above about 32 degrees Fahrenheit, but thetemperature inside the structure is below the 50-65 degree Fahrenheitthermostat set point, the thermostat continues to call for heat eventhough it is not needed to prevent the structure's pipes from freezing.Such an arrangement can result in a significant amount of unnecessaryheating, and consequently of unnecessary energy use, and resultinggreenhouse gas emissions.

The method and system disclosed herein cause increases in the indoortemperature of a structure in an inverse relationship to the outdoortemperature during periods of colder weather, for example, when there isa danger of damage to the indoor space from cold weather.

The present disclosure provides a method and apparatus to address theproblem of unnecessary heating of unoccupied structures. A structurecomprises indoor space, or simply “space,” in which objects, animals orpeople can be disposed. The indoor space is separated from outdoor spaceby one or more walls. As used herein, the term “wall” does not requirethat the wall extend vertically or substantially vertically. Rather,walls can extend horizontally or substantially horizontally, such as inthe case of a floor or a ceiling; or walls can extend neither verticallynor horizontally, such as a pitched roof.

The method described herein can be used to control the temperature inany suitable indoor space. Suitable indoor spaces include, but are notlimited to, a residence, a commercial building, and a moveable space. Aresidence can be, but is not limited to, one or more of a detached homeand a multi-family residential dwelling. A multi-family residentialdwelling can be, but is not limited to, one or more of a duplex, asemi-detached home, a townhouse, an apartment, a condominium and aco-op. A commercial building can be, but is not limited to, one or moreof an office space, an office building, a retail space, an industrialbuilding and a storage building. A moveable indoor space can be, but isnot limited to, one or more of a train wagon, a ship, a boat, anairplane, a recreational vehicle and a mobile home.

In one embodiment, the system can be configured to function in a vacantbuilding, for example one which can be for sale or rent, and which doesnot have wireless Internet service. In these circumstances, it isanticipated that remote communication with the system can beaccomplished through a cellular telephone network or other wirelesstechnology, either directly with the heating control system, or via aseparate apparatus within the building and in proximity to the heatingcontrol system, and communicating with the heating control system eitherthrough a wired connection, or through a wireless method or via athermal interface. The cost of such a simple configuration isanticipated to be modest in comparison to the energy savings to berealized by implementing the present invention.

The method can be implemented on an apparatus (a heating control system;eg, a thermostat) already resident in the structure, or can beimplemented by one or more heating control system designed specificallyto implement the method. The present disclosure provides a method forproviding sufficient heat to a structure to prevent damage from coldtemperatures or freezing pipes, while decreasing the overall energyusage of the structure.

Structures are heated or cooled by heating or cooling systems,respectively; and can be both heated and cooled by an integrated heatingand cooling system such as a HVAC (heating, ventilation and airconditioning) system. The present technology concerns itself withheating an indoor space, and therefore with a heating system or theheating component of an HVAC system. A heating system comprises at leastone heating mechanism (for example, a furnace) as well as a way to heatdirectly, such as electric resistance heat, or moving a heated fluidsuch as air or water through the structure. A heating system can be aheat-only system, or, for the purposes of this disclosure, the heatingcomponents of an HVAC system, either of both which meanings, as well asequivalents thereof, are encompassed by the use of “heating system”herein.

The methods and systems disclosed herein can be used with any type ofheating system. The heating system can be a heat-only system. Theheating system can be a heating, ventilation and air conditioning (HVAC)system. The heating system can be a forced-air system. The heatingsystem can be a radiant heating system. The radiant heating system cancomprise one or more of electric resistance heat elements, traditionalradiators, under-floor heating elements, and behind-wall heatingelements. The heating system can be produce heat in any way known tothose skilled in the art. The heating system can, for example, useelectricity, or burn fuels such as natural gas, LP, propane or fuel oil.

A heating system comprises at least a furnace and a furnace controlsystem. As used herein, the term furnace is a generic term encompassingthe heating element of all types of heating systems. “Furnace,” as usedherein, includes but is not limited to a furnace, a boiler, a heat pump,an electrical resistance heater, a geothermal based system, a solarsystem, a wood-burning heater, a fossil fuel-burning heater, and othertypes of heating systems.

Furnaces are activated by a furnace control system. The furnace controlsystem can receive signals from a heating control system. The heatingcontrol system is usually, though not always, separate from the furnacecontrol system. The heating control system can be connected to thefurnace control system by wired circuits, wireless apparatus, opticalfibers, or any other method that allow signaling to call for heat.

A heating system can be controlled by a heating control system.Generally, heating control systems provide a way for a heating system torespond to user requirements for an indoor space to be maintained at aparticular temperature. Heating control systems can comprise at leastone thermostat. The thermostat can read the temperature in the indoorspace in which it is installed, compare that temperature to apre-selected set point, and then, optionally, relay the need for heatingto the furnace control system. The furnace can then provide heat untilthe thermostat reads the temperature in the indoor space as equal to, orwithin a pre-selected range of, the set point.

In one embodiment, the methods described herein are implemented on, by,or in conjunction with a heating control system. The heating controlsystem can be co-located with the structure requiring heating, or cancontrol the heating system at the structure from a different physicallocation. In the case that the heating control system controls theheating system from a different physical location, the heating controlsystem and the heating system can be in communication through anymethod, including but not limited to electronic communication such as awired or wireless internet connection, satellite, cellular telephone orstandard telephone network.

In general, the present disclosure provides a method for controlling aheating system. Controlling the heating system of an indoor space cancomprise controlling the furnace control system to determine thetemperature to which the indoor space serviced by the heating system ismanaged. Control of the heating system can be accomplished by positivecontrol or negative control. In the case of positive control,controlling involves either calling for heat or selecting apredetermined set point managed by the furnace control system. Negativecontrol is prevention of the normal operation of the furnace controlsystem (calling for heat). The heating control system can be directlyconnected to the furnace control system. Alternatively, the heatingcontrol system can be connected to the furnace control system through anexisting temperature control apparatus such as a thermostat.

In one embodiment, a heating control system can be connected to anexisting temperature control apparatus through a thermal interface. Thethermal interface can produce heat, causing the temperature measuringdevices of the existing temperature control apparatus to register ahigher temperature than the ambient temperature of the space, therebypreventing the activation of the furnace control system that wouldotherwise occur. This is an example of negative control.

The method can comprise obtaining a reading for an outdoor temperature(To) indicator in proximity to at least one of the heating system and anindoor space. A reading for an outdoor temperature can be arepresentation of the outdoor temperature immediately outside the indoorspace, or at an outdoor location in proximity to at least one of theheating system, and the indoor space which is being heated thereby. Asused herein, “outdoor” is synonymous with “external”, “outside”,“atmospheric”, and other like terms. “Outdoor temperature,” “outdoorweather data,” “measured outdoor weather data” and other like termsinclude at least one of temperature and wind speed.

An outdoor temperature indicator, as understood in the disclosure andthe appended claims, can be any temperature which is reasonablyrepresentative of the outdoor weather conditions, including temperature,in proximity to, at or near the indoor space. For example, an outdoortemperature indicator can be an outdoor temperature which is directlymeasured, or can be a calculated outdoor temperature or calculatedoutdoor wind chill which is calculated from outdoor weather data whichis itself directly measured. An outdoor temperature indicator can be anoutdoor temperature which is obtained in real-time, or can be aforecasted outdoor temperature or forecasted calculated outdoor windchill. “Calculated outdoor weather data” or “calculated outdoor windchill” and other like terms are understood to be calculated based onmeasured outdoor weather data, including at least one of outdoortemperature or outdoor wind speed. The calculations performed to providea calculated outdoor wind chill can be performed at the site at whichthe outdoor weather information is gathered, at the site of a structurerequiring heating, or at any other site capable of performing suchcalculations. The measured or calculated outdoor weather data can bemeasured or calculated as an integer, or measured or calculated as areal number having one or more decimal places.

In one embodiment, wind chill can be calculated by methods standard inthe art. For example, wind chill can be calculated as in Equation 1.Wind Chill=35.74+0.6215 T−35.75(V^0.16)+0.4275 T(V^0.16)   Eq. 1

Where T is the outdoor air temperature in degrees Fahrenheit, and V isthe outdoor wind speed in miles per hour.

The measured outdoor weather data, including but not limited to at leastone of temperature and wind speed, can be measured by a sensor. Thesensor can be located at a site in proximity to the structure requiringheating. “In proximity to” is understood as encompassing one or moresites co-located with the structure requiring heating as well asencompassing one or more sites having outdoor weather which isrepresentative of the weather at the structure requiring heating. A siteor sites co-located with the structure is within five miles of thestructure, and ideally, within 100 yards, 10 yards, 5 yards, or 1 yardof the structure. The site or sites can be chosen based on variousfactors, including but not limited to, exposure to outdoor wind andexposure to sun. Sites “in proximity to” a structure requiring heatingshould be representative of the weather data at the site of thestructure requiring heating. For the purposes of this disclosure,“representative” weather data can be obtained from any source whichcollects such data, including a weather data site such as a NationalWeather Service site within 50 miles, 100 miles, or in somecircumstances, up to 200 miles, of a site, and can be obtained via anetwork such as a wired or wireless internet connection, satellite,cellular telephone or standard telephone network.

When the heating system is controlled based on outdoor weather dataobtained at a site in proximity to the structure comprising the heatingsystem or the indoor space, the measured outdoor temperature can beprovided directly, electronically via a network, such as a LAN network,a WAN network, the Internet (either wired or wirelessly), by Bluetooth,satellite, cellular phone network, standard telephone service, awireless mesh network, or by any combination of these methods.

Once obtained, the reading for an outdoor temperature indicator can becompared to a freeze protection point (P). The freeze protection pointcan be predetermined, or set by the user of the system or of the method.The freeze protection point can be 32 degrees or any temperature belowwhich it is advisable to further determine the need for additionalheating of the indoor space above the default set point. The freezeprotection point is a reference value used in determining if the defaulttemperature can be chosen as the set point. For outdoor temperaturesabove the freeze protection point, the default set point can beconsidered adequate to protect the indoor space from damage from lowtemperatures. During these times, significant amounts of energy can besaved by utilizing the default temperature set point, as compared tosystems that use a conventional fixed setting that does not adjust basedon outdoor temperature.

When the outdoor temperature is at or above the freeze protection point,the heating control system does not call for heat from the heatingsystem unless the indoor temperature is below the default set point. Thelower the freeze protection point is set, the greater the energy savingsthat the system and method deliver to the user.

When the outdoor temperature is below the freeze protection point, theheating control system can determine a computed set point (C) based onthe outdoor temperature indicator. Determining a computed set point canbe done mathematically, or by performing a set of logical steps, ie, asa logical function. One non-limiting example of such a logical-functionanalysis can be: IF outdoor temperature=20, THEN determine C to be 44.Another example of a logical-function analysis can be: IF outdoortemperature>=32, THEN determine C to be 36, ELSE determine C to be 55.The result of such a logic function analyses can be a set of points thatlook like a stepped function (810) such as that shown in FIG. 8.

The computed set point can be an integer, or a real number having one ormore decimal places. The computed set point can increase monotonicallyas the outdoor temperature decreases below the freeze protection point.Those having ordinary skill will recognize that the rate of change ofthe computed set point, referred to herein as a scaling factor(s), canvary across various ranges of outdoor temperatures, producing a set ofcomputed set points in response to changes in outdoor temperature that,when graphed, produce a curved line (830). The scaling factor can be aninteger, or a real number having one or more decimal places. A scalingfactor can be about 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2,1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6,2.7, 2.8, 2.9, or 3.0. The computed set point can be determined using alinear function, or it can utilize one or more higher order factorsresulting in a curved function.

The computed set point can be compared to a default set point (D). Thedefault set point can be any temperature close to freezing, but whichhas been determined to be a temperature at which the structure and/orits contents will not be damaged. When protecting against damage causedby the freezing of water, such as water standing in pipes, preferably,the default set point is one, two, three, four or five degrees abovefreezing, or 33, 34, 35, 36 or 37 degrees Fahrenheit; or from six to tendegrees above freezing, or 38, 39, 40, 41, or 42 degrees Fahrenheit. Inthe non-limiting embodiment shown in FIG. 4, the default set point forthe heating control system is 36 degrees Fahrenheit. The default setpoint is the lowest set point to which, when the method is being used,the heating control system can be set.

The computed set point can be compared to a maximum set point (M). Themaximum set point is the highest set point to which, when the method isbeing used, the heating control system can be set.

A chosen set point can be selected. The chosen set point is the point towhich the heating control system controls the heating system to provideheat the indoor space. The chosen set point is selected by selecting oneof: (1) the default set point if the computed set point is below thedefault set point; (2) the computed set point, if the computed set pointis between the default set point and the maximum set point; or (3) themaximum set point, if the computed set point is above the maximum setpoint. Generally, the chosen set point increases as outdoor temperaturedecreases below the freeze protection point. See FIG. 8 for severalexamples of ways in which the chosen set point can increase as theoutdoor temperature decreases.

The chosen set point can be determined using one or more scaling factorsother than 1.0 to create a more or less rapid change in the modulationof the indoor set point in response to changing outdoor temperatureindicators.

One or more of the default set point and maximum set points can be setat a point in time prior to the outdoor weather data being obtained, orone or more of the default set point and maximum set points can be setat a point in time subsequent to the outdoor weather data beingobtained.

Persons of ordinary skill in the art will recognize that it is alsopossible to apply logic similar to that described supra, but thatdetermines a computed set point without comparing the outdoortemperature to a freeze protection point. In this scenario, the computedset point can be determined and result in a negative (less than zero) orpositive (above zero) value depending on the outdoor temperature.

When one or more of outdoor weather data, a computed set point or achosen set point cannot be computed or obtained, a fail-safe set point(F) can be selected (325). The fail-safe set point can be set prior topracticing any or all other steps of the method, or at any point duringthe practice of the method. The fail-safe set point can be set by theuser at the time of failure of one or more of the steps of the method. Aheating control system implementing the method can advise a user of theheating control system that the fail-safe set point needs to be set. Aheating control system can advise a user of the heating control systemthat the fail-safe set point has been engaged. A fail-safe set point canbe in the range of 40-65 degrees Fahrenheit, or it can be any otherspecific temperature setting which the user defines. A differentfail-safe set point can also be set for each month or even week of aheating season. For example, when choosing a fail-safe temperature foran indoor space in Alexandria, Va., one can choose a higher fail-safetemperature such as 60 degrees for the colder winter months of December,January, and February, but choose lower fail-safe temperatures forNovember and March such as 50 degrees, and possibly even lower fail-safetemperatures for October and April such as 45 degrees.

The present disclosure provides a heating control system. The heatingcontrol system can comprise at least one user interface, and at leastone computer programmed to implement the steps of the method disclosedherein. The user interface can allow a user to program the heatingcontrol system, including but not limited to programming at least one ofa failsafe set point, a default set point, and a maximum set point. Thecomputer can be a general purpose computer; or it can be a specificpurpose computer, programmed specifically to implement the steps of thedisclosed method. The computer can store one or more of a user input oran outdoor temperature reading in a non-transitory medium. The computerthat performs the logical or mathematical operations of the method cancomprise a general purpose computer, and can also utilize applicationspecific integrated circuits (ASIC), field programmable logic arrays(FPGA), or any other implementation to perform all or part of themethod.

Generally, the heating control system can obtain a reading for anoutdoor temperature indicator signal in proximity to the heating systemand an indoor space. When the outdoor temperature indicator is at orabove a freeze protection point, the heating control system can select achosen set point by selecting a default set point. Alternatively, whenthe outdoor temperature indicator is below the freeze protection point,the heating control system can determine a computed set point based onthe outdoor temperature indicator, compare the computed set point to thedefault set point and a maximum set point, and select the chosen setpoint by selecting (1) the default set point if the computed set pointis below the default set point, (2) the computed set point, if thecomputed set point is between the default set point and the maximum setpoint, or (3) the maximum set point, if the computed set point is abovethe maximum set point. Once the chosen set point has been selected, theheating control system can control the heating system to regulate thetemperature of the indoor space according to the chosen set point.

The exact mathematical or logical function for computed set point andthe particular values chosen for the parameters, while important foroptimizing savings for a particular individual site and application,have only a minor impact on the overall results of the method.Regardless of the exact function used, substantially the same protectivebenefits and energy savings will be produced. The method, and anyapparatus using the method in conjunction with a heating system, willrealize the majority of the energy savings by enabling the use of a deepset back temperature, referred to herein as the default set point,across a wide range of outdoor temperatures prevalent during the heatingseason in many geographic regions, because the automatic adjustmentfeature will engage to provide protection needed.

Turning now to the figures.

FIG. 1 shows a representative schematic of a structure in which thedisclosed system and method can be used, including non-limitingplacement of the elements of the system in physical space.

A heating control system (108) can control a heating system. The heatingsystem can comprise a furnace (111) and a furnace control system (110),as defined herein.

The heating control system (108) can interact with an outdoortemperature sensor (107), which can sense the outdoor temperature at alocation in proximity to an indoor space (106), or with an outdoor windsensor (103), which can sense the outdoor wind speed at a location inproximity to the indoor space; or both. The heating control system (108)can interact with one or more wide area network (WAN) connections (104),either via a building network (105) (shown in FIG. 1) or directly (notshown). The WAN network can receive a reading for an outdoor temperaturerelayed from a weather data provider (100) through the Internet (101)and a WAN provider (102). The heating control system (108) can interactwith a temperature sensor (109), which itself can interact with athermal interface (112). The heating control system (108) can interactwith an ambient temperature sensor (113).

The heating system can be located in the same indoor section of thestructure, or it can be located in a different location in the structurefrom the heating control system (108).

The heating control system (108) can optionally include an apparatusthat controls the existing temperature control system through itstemperature sensor (109). This can be accomplished by controlling theapparent temperature the existing temperature control system reads fromthe original temperature sensor. A thermal interface (112) can generateheat in proximity to the original temperature sensor (109) and theapparatus can thereby control the actual ambient temperature through theuse of the set point of the original temperature control system. In thisembodiment, the apparatus can use an additional temperature sensor (113)to measure the actual temperature of the indoor space (106).

For example, when a constant 55 degree set point is set for an existingtemperature control system, the heating control system of the presentinvention, using a thermal interface, can provide heat to the originaltemperature sensor resulting in that sensor, and thereby the existingtemperature control system, to read an apparent temperature above 55degrees. The existing temperature control system would thereby refrainfrom calling for heat. In this example, the heating control system ofthe present invention effectively controls the ambient temperature bydeceiving the existing temperature control system. In one embodimentwhere the existing temperature control system is a thermostat, themethod and system of the present invention can be employed by adding theheating control system and a simple apparatus, a thermal interface, andwithout replacing the installed thermostat. This embodiment can enablesimplified and low cost implementation of the heating control system ofthe present invention in situations where replacing a thermostat is anundesirable option such as when a building is for sale or rent and isplanned to be vacant for a short period of time.

FIG. 2 illustrates a non-limiting example of a user interface screen(200). The current indoor temperature is displayed (202) along with theoutdoor temperature (203). Across the bottom are icons for settingparameters for fail-safe set point (204), default set point (205),maximum set point (206), freeze protection point (207), and scalingfactor (208). In the upper left, the chosen set point (201) is shown.

FIG. 3 shows the general method disclosed herein, and which a system ofthe present disclosure can implement. As a general first step, a systemcan automatically obtain or attempt to obtain an outdoor temperatureindicator signal (310). The reading can be obtained at any site inproximity to a structure in which the method is being implemented. Ifthe outdoor temperature is not available (320), a fail-safe set point isselected (325). The fail-safe set point is any set point for a heatingcontrol system which is believed to adequately protect a structureagainst damage from any cold temperature. If the outdoor temperatureindicator is available (320) and is at or above the freeze protectionpoint (330), the default set point is selected (335). The default setpoint can be pre-set or is any set point which the user defines, andwhich is low enough to achieve significant energy savings as compared tosystems which use standard fixed set points, for example 50-65 degrees,for unoccupied structures. The use of this relatively low default setpoint is possible by the automatic adjustment to set point when colderoutdoor temperatures occur. Examples of this will be discussed below. Ifthe outdoor temperature indicator is lower than the freeze protectionpoint (330), then the computed set point is determined based on outdoortemperature indicator (340).

In an exemplary, non-limiting embodiment, the computed set point can becalculated (340) asC=(32−To)s+32, where:

s=scaling factor; any real number between and including about 0.3 andabout 3.0

To=outdoor temperature

If the outdoor temperature indicator is below the freeze protectionpoint, the computed set point is determined (340) based on outdoortemperature, forecast of outdoor temperature, wind chill, or forecastedwind chill, and compared (350) to the default set point, whichessentially serves as the minimum set point, as well as a maximum setpoint, above which the set point will not be permitted. The default setpoint is chosen (335) if the computed set point is less than the defaultset point (360). The computed set point is chosen (375) if it is betweenthe default set point and the maximum set point. The maximum set pointis chosen (365) if the computed set point is above the maximum setpoint. The heating control system controls the heating system toregulate the temperature of the indoor space to the chosen set point.

The general logic of a method for controlling a heating system, andwhich can be implemented on a heating control system, is shown in FIG.3. One skilled in the art will recognize that, once the reading for anoutdoor temperature is obtained, the order of the logical steps can bealtered somewhat, while achieving substantially the same result. Forexample, the outdoor temperature indicator can be obtained and thencompared to a freeze protection point first, as shown, to determinewhether the default set point can be used. If the outdoor temperatureindicator is low enough that the default set point is not used, acomputed set point can then be determined and compared to the defaultset point and the maximum set point and a chosen set point can bechosen. Alternatively, the computed set point can be determined, withoutcomparison to a freeze protection point, based on the outdoortemperature indicator and then compared to the default set point andmaximum set point temperatures to determine a chosen set point.

FIG. 4 shows two examples of graphical representations of the chosen setpoint produced by the method described herein. Both lines show a defaultset point (420) of 36 and a maximum set point (430) of 75. One lineshows line slope resulting from a scaling factor of 1.0 (400), while thesecond shows a steeper line (410) with a scaling factor of 1.5 which, ineffect, raises the computed indoor set point more quickly in response tofalling outdoor temperature.

FIG. 5 shows an additional example of a graphical representation of thechosen set point (500) produced by the method described herein. Thedefault set point (520) is 36, the maximum set point (530) is 65, andthe slope of the line, which determines how quickly the computed setpoint changes as a function of outdoor temperature, is 0.8.

FIG. 6 shows a conventional fixed setback (620) using a set point of 55°F. In contrast, an example of the set points resulting (630) fromutilizing one embodiment of the present invention is shown. When theoutdoor temperature indicator is above the freeze protection point, thedefault setting is chosen, in this case with a set point of 36° F. Inthis example, the computed indoor set points are shown increasing by 1°F. for each degree the outdoor temperature decreases below freezing.With an outdoor temperature reading of 10° F., the resulting indoor setpoint is 54° F. In this example, at all times when outdoor temperaturesare above 9°, energy will be saved over the use of a conventional fixedsetback of 55° F. For this computed set point function, FIG. 6demonstrates this breakeven point (610). In this particular example,where a scaling factor of 1.0 is being used, only when outdoortemperatures decline below 9° will the present invention use more energyto protect the indoor space from freezing than a conventional fixedsetback scheme of 55 degrees. The benefit from additional heating inthis example, as outdoor temperatures decline below 9 degrees F., isincreased protection against the risk of freezing.

FIG. 7 shows a comparison of relative costs for three different fixedheating control system settings. These costs are based on the USDepartment of Energy's approximation for savings achieved by turningdown a heating control system during the heating season. The first bar(700), is the base case. It considers as full cost, the energy needed toheat a home to 68°. The next bar (710), reflects 39% savings by settingthe thermostat to a fixed setting of 55° for 24 hours per day. The costof heating, in this example, is estimated to be 61% of the base case.During times (720) when the heating control system chooses the defaultset point, i.e. is set back to 36° for example, it is estimated that theenergy cost could be reduced to 26% of the original base case.

FIG. 8 shows three different functions for determining set points acrossvarious outdoor temperatures. Persons of ordinary skill in the art willrecognize that determining a computed set point can be accomplishedusing a linear function, or it can be accomplished utilizing one or morehigher order factors to produce a curved function. One example of acurved function for computed set points is shown (830) in FIG. 8. Setpoint rates of change can vary across the range of outdoor temperatures,producing a curved response in computed set points to changes in outdoortemperature. Straight line functions are possible (820), as previouslymentioned, as are stepped functions (810) that can occur by selecting achosen set point using if-then-else logical determination methods.

EXAMPLES

The following examples describe particular, non-limiting embodiments ofthe described method and system. For simplicity, all of the examples useoutdoor temperature as the outdoor temperature indicator. A personhaving ordinary skill in the art will readily understand how the otheroutdoor temperature indicators described herein can be utilized todetermine computed set points.

Example 1

The system and method provides both a default set point, below which thesystem will not let the temperature fall; and a maximum set point, abovewhich the system will not heat. The following examples use 36 degreesFahrenheit as the default set point and 75 degrees as the maximum setpoint, but ordinarily skilled artisans will recognize that other setpoints can be selected for both the default and the maximum, asconsistent with a user's requirements, the system and method, and thelocation of a structure. Scaling factors can be selected based on auser's requirements, the system and method, and the location of thesystem, and they can also vary as outdoor temperature readings changeproducing curvilinear functions.

Parameters:

P=freeze protection point

D=default set point (serves as default and minimum set point)

M=maximum set point

F=fail-safe set point

s=scaling factor; any real number between and including about 0.3 andabout 3.0

To=outdoor temperature (obtained on-site or in proximity to thestructure being heated; or via weather service)

C=computed set point

General logic used to determine a chosen set point:

IF To is not available, THEN F

IF To>=P, THEN D

IF To<P, THEN find C, (IF C cannot be determined, THEN F)

IF C<D, THEN D

IF C>=D, AND IF C<=M, THEN C

IF C>M, THEN M

Example 2

An exemplary method of controlling a heating system is described below.

Parameters:

P=32

D=36

M=75

F=55

s=1.0

Logic: Given outdoor temperature To=40, then the computed set pointC=24. In this example, the chosen set point=36 or D, the default setpoint, since C<D. Since the outdoor temperature is warmer than theindoor set point, unnecessary active heating of the indoor space will beavoided.

Example 3

This example shows that the disclosed method can cause a heating controlsystem to adjust indoor temperatures upward as outdoor temperaturesdecrease below a freeze protection point. In this example, a heatingcontrol system controls a heating system to heat a structure the samenumber of degrees above freezing that the outdoor temperature is belowfreezing, i.e, the method controlling the heating control systemoperates as a linear function where the scaling factor s=1.0.

Parameters:

P=32

D=36

M=75

F=55

s=1.0

To=22

C=42

Logic: Given outdoor temperature To=22, then the computed set point C=42and the chosen set point is also 42 since D<C<M.

Since the outdoor temperature is obtainable and is below the freezeprotection point P, a computed set point is determined. In thisnon-limiting example, the heating control system controls the heatingsystem to regulate the temperature of the indoor space according to thechosen set point of 42 degrees. This result can be found on the function400, FIG. 4.

Example 4

This example shows that the disclosed method can cause a heating controlsystem to adjust indoor temperatures upward as outdoor temperaturesdecrease below a freeze protection point. In this example, a heatingcontrol system controls a heating system to heat a structure the samenumber of degrees above freezing that the outdoor temperature is belowfreezing, i.e, the method controlling the heating control systemoperates as a linear function where the scaling factor s=1.0.

Parameters:

P=32

D=36

M=75

F=55

s=1.0

To=45

C=19

Using the same logic as described in Example 1, when the outdoortemperature is 45 degrees Fahrenheit, the default set point is chosenbecause the outdoor temperature is above the freeze protection point P.If for some reason the freeze protection point is not used, a computedset point of 19 could still be determined; 19 is compared to a defaultset point D of 36 and a maximum set point M of 75; the default set pointD is chosen because the computed set point falls below the default setpoint D.

Example 5

This example shows that the disclosed method can cause a heating controlsystem to adjust indoor temperatures upward to a user-defined maximumset point as outdoor temperatures decrease well below a freezeprotection point. In this example, a heating control system controls aheating system to heat a structure the same number of degrees abovefreezing that the outdoor temperature is below freezing until themaximum set point is reached, i.e, the method controlling the heatingcontrol system operates as a linear function where the scaling factors=1.0, until the maximum set point is reached.

Parameters:

P=32

D=36

M=75

F=55

s=1.0

To=−25

C=89

Using the same logic as described in Example 1, when the outdoortemperature is −25 degrees Fahrenheit, a computed set point C of 89 isdetermined. In this example, the computed set point C of 89 is comparedto the maximum set point M of 75; the maximum set point M is chosenbecause the computed set point C falls above the maximum set point M.

Example 6

In this example, the indoor temperature is raised 1.5 degrees for everydegree that the outdoor temperature drops below the freeze protectionpoint P.

Parameters:

P=32

D=36

M=75

F=55

s=1.5

To=22

C=47

Logic: Given outdoor temperature To=22, then the computed set point C=47and the chosen set point is also 47 since D<C<M. This result can befound on the function 410, FIG. 4.

Example 7

In this example, the indoor temperature is raised 1.5 degrees for everydegree that the outdoor temperature drops below the freeze protectionpoint P.

Parameters:

P=32

D=36

M=75

F=55

s=1.5

To=45

C=47

When the outdoor temperature is 45 degrees Fahrenheit, i.e. above thefreeze protection point, the danger of damage from freezing is notpresent, and the default set point D is chosen; and the heating systemis controlled to provide heat, only as necessary, to keep the indoorspace at the default set point D of 36 degrees Fahrenheit.

Example 8

This example shows that the disclosed method can cause a heating controlsystem to adjust indoor temperatures upward to a user-defined maximumset point as outdoor temperatures decrease well below a freezeprotection point. In this example, a heating control system controls aheating system to heat a structure until the maximum set point isreached. In this example, the computed set point is a linear functionwhere the scaling factor s=1.5, until the maximum set point is reached.

Parameters:

P=32

D=36

M=75

F=55

s=1.5

To=−25

C=117.5

As a further alternative, when the outdoor temperature is −25 degreesFahrenheit, a computed set point C of 117.5 is determined; 117.5 iscompared to the maximum set point M of 75; the maximum set point ischosen because the computed set point C falls above the maximum setpoint M; and the heating control system controls the heating system toregulate the temperature of the indoor space according to the chosen setpoint of 75 degrees.

What is claimed is:
 1. A method for automatically operating athermostatic heating system controller for controlling a heating systemfor heating an indoor space, comprising: operating the heating system ata set point having a default set point value set at less than 50 degreesFahrenheit; automatically receiving at least one indoor temperaturesignal from at least one indoor temperature sensor representing one ormore temperature measurements in the indoor space; automaticallyreceiving at least one outdoor weather indicator signal representing ameasured or predicted outdoor weather condition; based at least in parton the at least one outdoor weather indicator signal, determining afactor affecting heat flow out of water pipes adjacent to said indoorspace; comparing said factor affecting heat flow to a pre-determinedfreeze protection point; based on said comparison, determining whetherto maintain said set point at said default set point value or to raisesaid set point to a computed set point value which is higher than thedefault set point value, in response to determining to raise the setpoint to the computed set point value, computing the computed set pointvalue based at least in part on said outdoor weather indicator signal,followed by raising the set point to the computed set point value; andusing the thermostatic heating system controller to automaticallycontrol the heating system based on a comparison of the indoortemperature signal and the set point.
 2. A heating system comprising: afurnace for heating an indoor space; at least one heating systemcontroller operatively connected to said furnace, said heating systemcontroller comprising a thermostat; a receiver operatively connected tosaid heating system controller for automatically receiving a signalindicative of a measured or predicted outdoor weather condition; whereinthe at least one heating system controller is adapted to: operate thefurnace to maintain the temperature in said indoor space at a set pointhaving a default set point value set at less than 50 degrees Fahrenheit;automatically receive at least one outdoor weather indicator signalrepresenting a measured or predicted outdoor weather condition; based atleast in part on the at least one outdoor weather indicator signal,determine a factor affecting heat flow out of water pipes adjacent tosaid indoor space; compare said factor affecting heat flow to apredetermined freeze protection point; based on said comparison,determine whether to maintain said set point at said default set pointvalue or to raise said set point to a computed set point value which ishigher than the default set point value, and in response to determiningto raise the set point to the computed set point value, computing thecomputed set point value based at least in part on said outdoor weatherindicator signal, followed by raising the set point to the computed setpoint value; and automatically control the heating system based on acomparison of the indoor temperature signal and the set point.
 3. Themethod of claim 1 wherein the factor affecting heat flow is an outdoortemperature indicator.
 4. The method of claim 3 wherein the at least oneoutdoor weather indicator signal represents at least one of a measuredoutdoor temperature provided by a weather data service provider or ameasured wind speed provided by a weather data service provider.
 5. Themethod of claim 3 wherein the at least one outdoor weather indicatorsignal represents at least one of a forecast of outdoor temperatureprovided by a weather data service provider, a forecast of wind speedprovided by a weather data service provider, or a forecast of wind chillprovided by a weather data service provider.
 6. The method of claim 3wherein the at least one outdoor weather indicator signal is generatedby a sensor located on the same real property as the indoor space. 7.The method of claim 3 wherein the outdoor temperature indicatorcomprises a present or predicted outdoor temperature, or a present orpredicted wind chill.
 8. The method of claim 3, wherein said heatingsystem controller comprises an indoor temperature sensor and a thermalinterface comprising a heating element deployed adjacent said sensor,and wherein using the heating system controller to automatically controlthe heating system comprises using the heating element of the thermalinterface to control the output of the temperature sensor.
 9. The methodof claim 3 wherein the at least one outdoor weather indicator signal isprovided by a weather data service provider.
 10. The method of claim 1wherein the default set point is in a range of 32.0 to 39.0 degrees F.11. The method of claim 1 wherein the default set point is less than 43degrees F.
 12. The method of claim 1 wherein the at least one indoortemperature signal is based on information from at least two sensors.13. The method of claim 12 wherein the indoor space is a residentialspace.
 14. A heating system controller adapted for controlling athermostat for an indoor space, said thermostat having a first indoortemperature sensor, comprising: one or more processors adapted to:operate the thermostat at a set point having a default set point valueset at less than 50 degrees Fahrenheit; automatically receive at leastone outdoor weather indicator signal representing a measured orpredicted outdoor weather condition; based at least in part on the atleast one outdoor weather indicator signal, determine a factor affectingheat flow out of water pipes adjacent to said indoor space; compare saidfactor affecting heat flow to a pre-determined freeze protection point;based on said comparison, determine whether to maintain said set pointat said default set point value or to raise said set point to a computedset point value which is higher than the default set point value, and inresponse to determining to raise the set point to the computed set pointvalue, computing the computed set point value based at least in part onsaid outdoor weather indicator signal, followed by raising the set pointof the thermostat to the computed set point value.
 15. The controller ofclaim 14 wherein the factor affecting heat flow is an outdoortemperature indicator.
 16. The controller of claim 15 wherein theoutdoor temperature indicator comprises a present or predicted outdoortemperature, or a present or predicted wind chill.
 17. The controller ofclaim 15 wherein the default set point is less than 40.0 degrees F. 18.The controller of claim 15 wherein the controller is adapted to receivethe at least one outdoor weather indicator signal provided from aweather data service provider.
 19. The controller of claim 15 whereinthe controller is adapted to receive the at least one outdoor weatherindicator signal from a sensor located on the same real property as theindoor space.
 20. The controller of claim 15 wherein the one or moreprocessors are further adapted to automatically receive at least oneindoor temperature indicator signal representing one or more temperaturemeasurements of the indoor space from a sensor which is additional to,and spaced apart from, said first indoor temperature sensor.